
        var context;

        var arr = new Array();
        var starCount = 800;

        var rains = new Array();
        var rainCount = 20;

        var windowWidth;

        //初始化画布及context
        function init() {
            //获取canvas
            var stars = document.getElementById("stars");
            windowWidth = window.innerWidth; //当前的窗口的高度
            stars.width = windowWidth;
            stars.height = window.innerHeight;
            //获取context
            context = stars.getContext("2d");
        }

        //创建一个星星对象
        var Star = function () {
            this.x = windowWidth * Math.random();//横坐标
            this.y = 5000 * Math.random();//纵坐标
            this.text = ".";//文本
            this.color = "white";//颜色

            //产生随机颜色
            this.getColor = function () {

                var _r = Math.random();

                if (_r < 0.5) {
                    this.color = "#333";
                } else {
                    this.color = "white";
                }

            }

            //初始化
            this.init = function () {
                this.getColor();
            }
            //绘制
            this.draw = function () {
                context.fillStyle = this.color;
                context.fillText(this.text, this.x, this.y);
            }

        }

        //画月亮
        function drawMoon() {
            var moon = new Image();
            moon.src = "../images/login/moon.png"
            context.drawImage(moon, -5, -10);
        }




        //星星闪起来
        function playStars() {
            for (var n = 0; n < starCount; n++) {
                arr[n].getColor();
                arr[n].draw();
            }

            setTimeout(playStars, 100);
        }


        /*流星雨开始*/

        var MeteorRain = function () {
            this.x = -1;
            this.y = -1;
            this.length = -1;//长度
            this.angle = 30; //倾斜角度
            this.width = -1;//宽度
            this.height = -1;//高度
            this.speed = 1;//速度
            this.offset_x = -1;//横轴移动偏移量
            this.offset_y = -1;//纵轴移动偏移量
            this.alpha = 1; //透明度
            this.color1 = "";//流星的色彩
            this.color2 = "";  //流星的色彩
            /****************初始化函数********************/
            this.init = function () //初始化
            {
                this.getPos();
                this.alpha = 1;//透明度
                this.getRandomColor();
                //最小长度，最大长度
                var x = Math.random() * 80 + 150;
                this.length = Math.ceil(x);
                //                  x = Math.random()*10+30;
                this.angle = 30; //流星倾斜角
                x = Math.random() + 0.5;
                this.speed = Math.ceil(x); //流星的速度
                var cos = Math.cos(this.angle * 3.14 / 180);
                var sin = Math.sin(this.angle * 3.14 / 180);
                this.width = this.length * cos;  //流星所占宽度
                this.height = this.length * sin;//流星所占高度
                this.offset_x = this.speed * cos;
                this.offset_y = this.speed * sin;
            }

            /**************获取随机颜色函数*****************/
            this.getRandomColor = function () {
                //var a = Math.ceil(255 - 240 * Math.random());
                //中段颜色
                this.color1 = "#55b3d3";
                //结束颜色
                this.color2 = "#010c21";
            }


            /***************重新计算流星坐标的函数******************/
            this.countPos = function ()//
            {
                //往左下移动,x减少，y增加
                this.x = this.x - this.offset_x;
                this.y = this.y + this.offset_y;
            }

            /*****************获取随机坐标的函数*****************/
            this.getPos = function () //
            {
                //横坐标200--1200

                this.x = Math.random() * window.innerWidth; //窗口高度
                //纵坐标小于600
                this.y = Math.random() * window.innerHeight;  //窗口宽度
            }
            /****绘制流星***************************/
            this.draw = function () //绘制一个流星的函数
            {
                context.save();
                context.beginPath();
                context.lineWidth = 1; //宽度
                context.globalAlpha = this.alpha; //设置透明度
                //创建横向渐变颜色,起点坐标至终点坐标
                var line = context.createLinearGradient(this.x, this.y,
                    this.x + this.width,
                    this.y - this.height);



                //分段设置颜色
                line.addColorStop(0, "#55b3d3");
                line.addColorStop(0.3, this.color1);
                line.addColorStop(0.6, this.color2);
                context.strokeStyle = line;
                //起点
                context.moveTo(this.x, this.y);
                //终点
                context.lineTo(this.x + this.width, this.y - this.height);
                context.closePath();
                context.stroke();
                context.restore();
            }
            this.move = function () {
                //清空流星像素
                var x = this.x + this.width - this.offset_x;
                var y = this.y - this.height;
                context.clearRect(x - 3, y - 3, this.offset_x + 5, this.offset_y + 5);
                //                  context.strokeStyle="red";
                //                  context.strokeRect(x,y-1,this.offset_x+1,this.offset_y+1);
                //重新计算位置，往左下移动
                this.countPos();
                //透明度增加
                this.alpha -= 0.002;
                //重绘
                this.draw();
            }

        }

        //绘制流星
        function playRains() {

            for (var n = 0; n < rainCount; n++) {
                var rain = rains[n];
                rain.move();//移动
                if (rain.y > window.innerHeight) {//超出界限后重来
                    context.clearRect(rain.x, rain.y - rain.height, rain.width, rain.height);
                    rains[n] = new MeteorRain();
                    rains[n].init();
                }
            }
            setTimeout(playRains, 2);
        }


        /*流星雨结束*/


        
        //页面加载的时候
        function load() {
            init();
            //画星星
            for (var i = 0; i < starCount; i++) {
                var star = new Star();
                star.init();
                star.draw();
                arr.push(star);
            }

            //画流星
            for (var j = 0; j < rainCount; j++) {
                var rain = new MeteorRain();
                rain.init();
                rain.draw();
                rains.push(rain);
            }

            drawMoon();//绘制月亮
            playStars();//绘制闪动的星星
            playRains();//绘制流星

        }

        export default load
